Fan for a food freezer

ABSTRACT

A fan for cold gas circulation in a food freezer has fan blades mounted on a hub. The hub is formed from two stainless steel plates, and the fan is formed by locating the fan blades situated between the stainless steel plates.

This application claims the priority of German Application No. 102004020178.1, filed Apr. 22, 2004, the disclosure of which is expressly incorporated by reference herein.

This invention relates to a fan for circulating cold gas in a food freezer, wherein the fan has blades mounted on a hub.

A wide variety of equipment in which the foodstuffs are exposed to a cold gas atmosphere, e.g., a nitrogen gas atmosphere, is used for refrigerating or freezing foodstuffs. The cold gas atmosphere may be created, for example, by evaporating a liquefied gas, e.g., liquid nitrogen. To achieve a uniform distribution of the cold gas and thus efficient cooling of foodstuffs, fans are provided for the required cold gas circulation. Depending on the design of the freezer, we speak of chest freezers, tunnel freezers or spiral belt freezers. With the very popular tunnel freezers, the foodstuffs are placed on a conveyor belt, for example, that conveys the foodstuffs through a tunnel-like housing. A cold gas atmosphere is maintained in the tunnel-like housing, usually with multiple fans providing the required cold gas circulation. The fans used are very often of the type in which the blades of the fan are made of plastic and the hub of the fan is made of aluminum. However, use of aluminum is problematical in the food area for hygiene reasons, due to corrosion and in particular due to cleaning agents. On the other hand, solid hubs made of stainless steel are very expensive and are complex to manufacture. The die-casting molds used to produce them have very short lifetimes.

Therefore, the object of the present invention is to make available a fan for cold gas circulation in a food freezer which will at the same time meet high demands regarding hygiene and will have a high efficiency.

This object is achieved according to this invention by the fact that the hub is made of two sheets of stainless steel with the fan blades situated between them.

Fans which have previously been made entirely of stainless steel with a solid stainless steel hub and stainless steel blades have a very low efficiency, so that recently fans with plastic blades and aluminum hubs have been used to increase performance. However, such high-power fans do not meet the highest demands regarding hygiene because of corrosion problems. A solution to this problem has been found with the present invention, meeting demands with regard to efficiency as well as food hygiene at the same time. The hub is not designed as a solid stainless steel hub but instead is simply comprised of two stainless steel plates, so the mass of the fan to be accelerated is much lower and therefore the efficiency is higher. In addition, fabrication is greatly simplified in comparison with solid stainless steel hubs. On the other hand, there are no corrosion problems due to the fact that it is made of stainless steel.

The stainless steel plates are expediently designed as circular disks. Near the circumference of the circle, each disk has boreholes for fastening the fan blades. Alternatively, these stainless steel plates may also be designed as pentagonal, hexagonal or octagonal disks. The fan blades are arranged in a sandwich construction between the two disks.

According to one refinement of the inventive idea, the stainless steel plates have cutouts which prevent food particles from accumulating. In addition, this facilitates cleaning on all sides inside and outside of the fan wheel. The cutouts may be designed in a variety of ways. The stainless steel plates are preferably manufactured by laser technology. In contrast with manufacturing solid stainless steel hubs, stainless steel plates may also be manufactured inexpensively by the laser technique. Alternatively, the stainless steel plates may also be milled.

To achieve a particularly high efficiency, the fan blades are advantageously made of plastic. However, they may also be made of stainless steel. The fan blades have an aerodynamically optimized profile (helicopter rotor).

The inventive fan may be used for all conceivable food freezers in which high demands of hygiene and efficiency are made. In particular the fan is suitable for chest freezers, tunnel freezers and spiral belt freezers.

This invention offers a number of advantages:

Due to the use of stainless steel for the hub and optionally plastic for the fan blade, the inventive fan is optimally suitable for use in food technology. Since corrosive materials are not used, the possibility of a chemical effect on the foodstuffs can be ruled out. Furthermore, due to the inventive design of the fan, dead space is minimized. Contamination of the foodstuffs due to adhering impurities can be reliably prevented. Finally, the fan can be manufactured by an inexpensive laser method.

Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows two stainless steel plates in accordance with an embodiment of the present invention in a view from above.

FIG. 2 shows a perspective diagram of a complete fan in accordance with an embodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 shows two stainless steel plates in the form of disks with an identical design so that when assembled they form the hub of the fan. In assembly, the two stainless steel plates are placed concentrically one above the other, with the opening 5 for the ventilator shaft and the boreholes 2, 3 to receive the fasteners for the fan blades are each situated above one another. The mass of the stainless steel plates is reduced and the accessibility for cleaning purposes is increased due to these recesses 4.

FIG. 2 shows on the left side a completely assembled fan in a perspective diagram as seen from above while it is shown from beneath on the right side. At the center can be seen a detailed view of the hub with stainless steel plates 1 and 2 and the fan blades 8 mounted thereon.

The complete fan has a motor 6 which drives the hub which is composed of the stainless steel plates 1 and 2, via a shaft 7. The fan blades 8 are each inserted at one end into the intermediate space formed by the stainless steel plates 1 and 2 and fastened there to the stainless steel plates 1 and 2 by means of bolts or screws, for example.

The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof. 

1. Fan for cold gas circulation in a food freezer, wherein the fan has fan blades mounted on a hub, wherein the hub is comprised of two stainless steel plates with the fan blades situated between them.
 2. Fan as claimed in claim 1, wherein the stainless steel plates are circular disks.
 3. Fan as claimed in claim 1, wherein the stainless steel plates are pentagonal, hexagonal or octagonal disks.
 4. Fan as claimed in claim 1, wherein the stainless steel plates have cutouts.
 5. Fan as claimed in claim 1, wherein the stainless steel plates are manufactured by laser method.
 6. Fan as claimed in claim 1, wherein the stainless steel plates are milled.
 7. Fan as claimed in claim 1, wherein the fan blades are made of plastic.
 8. Fan as claimed in claim 1, wherein the fan blades are made of stainless steel.
 9. A fan for cold gas circulation in a food freezer, comprising: two stainless steel fan hub plates; and a plurality of fan blades, wherein the stainless steel plates are spaced apart from one another on a concentric axis, and a hub end of each of the plurality of fan blades is located between the plates. 